Relief is finally in sight from the bitter cold that gripped its hold on the region for weeks, but with it comes concern about flooding from melting mounds of snow.
Ben Deubelbeiss, meteorologist with the National Weather Service in Romeoville, said Thursday is supposed to start a warming trend, with temperatures reaching 33 degrees.
"It does look like, for the most part, the pattern is changing for the warmer," Deubelbeiss said.
The higher temperatures bring with them a fear of flooding. Deubelbeiss said the liquid water equivalent in the snowpack on the ground is 1 to 3 inches, meaning if all the snow were to melt, it would equal 1 to 3 inches of water.
A chance of snow or rain is forecast Thursday through Monday, meaning the melting snow also will have additional precipitation added to the mix.
"With the frozen ground already saturated, the melting snow and new precipitation will pretty quickly turn to runoff, which will run over the land into streams or rivers," Deubelbeiss said.
"Certainly flooding is a concern we'll be watching closely."
Deubelbeiss said temperatures above freezing Thursday will give way to highs in the 20s through Sunday, which is good news. The gradual increase in temperatures should make for a slower thaw and less of a rush of water over the ground, at least through the weekend, he said.
Temperatures are expected to rise again Monday. Deubelbeiss said a system expected to move in Monday has the potential to bring significant precipitation. It is too early to predict just how much, he said, but forecasters will be watching it closely.
The National Weather Service only extends forecasts for seven days, but some forecasts are predicting temperatures above freezing all of next week, with a high next Thursday near 50 degrees.
That is when real problems could surface.
Porter County Surveyor and Drainage Board member Kevin Breitzke said problems could arise around the county, particularly along the Kankakee and Little Calumet rivers.
He has been in touch with the emergency management department, which is stocking up on sand and sandbags to make available to the public to combat rising waters.
The county highway department also is prepared to break up blockages within culverts under roads if a thaw occurs, Breitzke said.
A contractor is on standby to clear downed trees under bridges, he said.
"We're on guard," he said.
Lake County Surveyor Bill Emerson Jr. said he is working with the county Highway Department and municipalities on issues pertaining to the pending thaw.
"At the county complex, we pulled out the maps to make sure no snow mounds in the parking lots were on the drains," Emerson said.
He said his crews will be keeping an eye on waterways including the Kankakee River in south county, the Marsh Ditch and the Little Calumet River.
Highland Public Works Director John Bach said the catch basins and storm water system there can handle the melting snow.
"The challenge is going to be making sure that the water gets to the basins," Bach said.
He and other municipal leaders around the region encouraged residents to clear catch basin and stormwater grates near their homes to direct water from melting snow off the streets and into the proper systems.
Dan Repay, executive director of the Little Calumet River Basin Development Commission, said his group is watching the forecast.
"It's not like we can prevent it from happening," Repay said. "You just have to be prepared, and we are."
Times staff writers Bob Kasarda, Joyce Russell and Phil Wieland and Times correspondents Charles F. Haber and Jim Masters contributed to this report.